The inventive position indicator is for detecting and indicating the position of a member that moves along a predetermined path in discrete steps as part of the diaphragm of a still camera. In one type of automatic still camera it is necessary for the automatic control of the diaphragm to determine the actual diaphragm stop position and feed this information as a train of pulses to a digital computer circuit. Diaphragms for such systems have a member that moves axially upon adjustment of the diaphragm and a previously known way of determining the diaphragm position was to use a screened lamp transmitting light through an opening in the moving diaphragm part so that the light would fall on a plurality of photoelectric cells arranged along the path of movement to determine the position of the diaphragm. Pulses from the photoelectric cells are fed to a counter that determines diaphragm position by the pulse count.
Such an arrangement is very expensive, requires a hermetically sealed light arranged within the camera and consumes considerable power, which unreasonably shortens the operating life of the power source required for operating other electronic components within the camera.
The present invention involves recognition of the problems involved in previous diaphragm-position detecting and indicating systems, and a realization of a way that such a system can be made more simply and economically to produce the desired result without consuming any substantial energy. The invention aims at simplicity, economy, reliability, and low power consumption for a diaphragm-position detecting and indicating device.